The -clean switch shouldn't be used for Sysprep. It disables any boot devices that were loaded by the [SysprepMassStorage] section in the Sysprep.inf file. The command issues a stop command through Service Control Manager; any device that does not have hardware present responds to the command.

The -clean switch should only be used in the CMDLines.txt file to clean out unused drivers to help "imaged" PCs boot faster after being "sysprepped."